The purpose of these studies was to determine the effects of breakfast cereals with varying amounts of soluble and insoluble fiber combined with complex and simple carbohydrate on the metabolic response to long-term moderate intensity exercise. The influence of pre-exercise feedings of these cereals on exercise time to exhaustion was also determined. We hypothesized that breakfast cereals with a high soluble fiber content would produce a lower glycemic response than breakfast cereals with little or no soluble fiber; and that this lower glycemic response would provide longer lasting glucose availability during submaximal exercise. A more sustained glucose availability could decrease the rate of muscle glycogen utilization and enhance performance.